“125cc or 150cc will probably become the lower limit for small vehicles,” he says.

For now, that means the popular Honda Grom and Kawasaki Z125 Pro are safe.

Honda Grom

Kawasaki Z125 Pro

Tougher pollution restrictions

The axing of small-capacity motorcycles comes as Japan falls into line with global Euro4 pollution restrictions that require self-diagnostic emissions systems. These add to the cost of the bike while reducing the profit margin.

While Euro4 requires bikes to run clean for 20,000km, the introduction of Euro5 in 2020 requires those systems for the life of the bike, making them even more expensive to build.

The European Commission estimates that would add about $A160 to the cost of each vehicle which is about 10% of the price of some of these small-capacity models.

Yamaha CEO Hiroyuki Yanagi says it will make product development “extremely tough”.

“Instrument controls will become more complex, and costs will go up,” he says.

Worldwide impactHonda EV scooter

Manufacturers are expected to replace these small machines with electric vehicles which is the case in China.